The main purpose of a diesel fuel injector is to direct and atomize the metered fuel into a combustion chamber.
In a conventional fuel injector, a needle valve is disposed in the nozzle formed in a fuel injector. Fuel trapped in the nozzle is delivered into the combustion chamber according to up-down motion of the needle valve being controlled by a solenoid. Therefore, an operation time of the solenoid relates to a lift duration of the needle valve, determining the amount of fuel injected into a corresponding combustion chamber.
The trend in recent times is to make the nozzle as small as possible and increase the injection pressure to spray the fuel in more minute droplets and minimize the amount of fuel being injected during ignition delay timing such that fuel injection amounts can be better controlled and combustion efficiency can be improved.
However, the prior art fuel injector for diesel engines has a drawbacks in that there is a limit to minimize the injection fuel, since it is designed to simply supply the fuel pressurized only by the fuel pump to the combustion chamber by opening the nozzle hole.